The reliability of electronic components is of crucial importance in modern industry. There is an increasing demand for realistic predictions of the lifetimes of electronic components and of the variation of the components' parameter values over their lifetimes. The components of interest for such parameter value predictions include diodes, transistors, passive components such as metalization lines, wire bonds, resistors, capacitors, dielectrics, etc.
One method for predicting the value of a component's ageing parameter as a function of time is to place the component in an environment having an elevated temperature, perform a measurement of the parameter, and then repeat the cycle until sufficient measurements are made to permit a reliable prediction of the parameter value over time. However, because of the time required to perform this method it is particularly disadvantageous for systems wherein a small change of the parameter value occurs.
In European Patent Application EP-A-0395149, an in-situ component ageing technique is described, wherein it is possible to measure a component parameter value at an elevated temperature during a relatively short time period, typically on the order of 48 hours or less. In such a case, it is necessary that experimental errors in the collected data be minimized if extrapolation of the results to real operating conditions and future times are desired. In this technique, the oven in which the elevated temperature is achieved has a high temperature stability, e.g. on the order of .+-.0.01.degree. C., or even as small as .+-.0.001.degree. C.
Such a high degree of temperature stability is difficult to achieve and is sometimes accomplished by limiting the physical size of the oven, which generally permits better control of the temperature distribution within the oven. However, a disadvantage of limiting the physical size of the oven is that only one or a small number of components can be evaluated at the same time.
What is desired is an apparatus and method for obtaining high precision measurements of a component parameter which are corrected for temperature fluctuations occurring in an oven in which the measurements are made.